The present invention relates to ink jet printers and, more particularly, to pumping systems used to deliver ink from the ink source to the print head.
Inkjet printers are one of the most widely used print technologies, providing low cost, high speed, and high resolution printing. In order to print at high resolutions while maintaining high speed of operation, it is desired that a steady flow of ink is rapidly delivered to the print head. Various means have been employed in the art to deliver ink to the print head. Some ink jet systems, particularly the low-end models, have used disposable ink supply cartridges mounted on the print carriage, directly coupled to the print head. Other ink jet systems have used an electrically-powered pump to deliver the ink from a fixed supply tank to the print heads located on the print carriage.
U.S. Pat. Nos. 6,145,971 and 6,431,694 describe ink jet systems employing an ink pump driven by the motion of the print carriage; and, more specifically, driven by a passive inertial mass that moves in reaction to the acceleration of the print carriage. Such passively-driven ink pumps represent an important step in ink jet technology because they provide a mechanically simple pump that can be mounted directly on the print carriage. One of the shortcomings of this passively-driven ink pump seen in the prior art is the mass and, hence, the volume required to produce a pump that can achieve the pressures and flow rates required for commercial ink jet printers is too large. In order to supply enough force to generate the required pump capacity, the inertial mass as implemented in the prior art must be sufficiently large that it presents significant design limitations to the installation of the pump on the print carriage. If multiple ink pumps are required, as is necessary in a color printer, it becomes substantially difficult and impractical to fit the ink pumps on the print carriage due to their size.
In light of these shortcomings, there is a desire for a passive ink jet pump driven by an inertial mass that is smaller and lighter than those previously developed.